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Topic: 69 Penske vinyl roof (Read 10077 times)

In early 69 ,the Penske Camaro had a vinyl top. Some speculated ,this had a performance gain for some reason? It apears in pictures ,that they used lower trim at the bottom of this roof. Wouldn't this have caused a negative performance gain? I also noted that Donahue drove with the windshield wipers at verticle, which could have reduced drag.

From what I have read, and understand, the vinyl roof cover was an attempt to disguise the very thin, and prone to wrinkling acid dipped roofs. It seems to be that the vinyl actually drew more attention than if they had not been fitted.

The trim on the lower edge of the vinyll, whist not very aero, would not have been that bad in the greater scheme of things. The Camaro is a great looking car, the RS front would probably have been better than the regular grill as far as aero is concerned.

I don't believe ,that it would be smart to acid dip a roof. It's a major structural part of a uni body car. Convertibles have their frames reinforced. The roof may have been lowered ,and the vinyl was used to hide welds , and body work from sectioning. Mustangs raced at this time , had their front ends sectioned and lowered.

At the time there was a lot of speculation as to why the vinyl tops were on the Penske cars. People suspected lots of different reasons. I think one of the stranger hypotheses I've heard was that the vinyl top covered up tiny holes which released air pressure from inside the car. I don't think I have heard anything about a lowered roof but bondo and paint can cover up welds as good as any vinyl top can. I believe Mark Donohue was the one who stated that the vinyl tops were to cover up wavy roofs because the bodies of the two team cars had spent a little too much time in the acid tank. Yes, a normal unibody structure would suffer a lot from too much acid dipping and the roof does strengthen the structure of the body. However, don't forget that these cars had complete roll cages which attached to various parts of the chassis such as the front subframe, the rocker panels, the rear frame at the suspension pickup points, the side panels just aft of the door openings and it was also welded to the inner roof structure in a number of different spots. This is what became the birdcage type of frame for the car which was much stiffer than any unibody car, especially one without a B pillar behind the door, could be on its own.

Eventually, during the 1969 season the protesting of the vinyl tops got to be so much that Penske did have to have them removed and my understand is that the wavy roofs were cut off the cars and new roofs were rewelded in place, sans vinyl. It is a good thing, since Penske's cars finally started winning races with the vinyl tops off the cars and they went on to win the Trans-Am championship that year, making it two in a row.

I believe Bruce and Jon are right on with their responses. Though it's been documented by members of the Penske organization in more than one place, here's a quote on the vinyl top Camaros in Michael Argetsinger's book, Mark Donohue: Technical Excellence at Speed.

"While the Penske refueling tower was causing a great deal of official concern, there was also a rustle of unhappiness over the appearance of the Sunoco Camaros. The cars appeared with vinyl (or Landau) tops, and had the entire paddock talking. 'We were running Landau roofs because the roofs were too thin,' says Woody Woodard. Soon after Woody came to work at Newtown Suare, he flew with Mark to Los Angeles where the new bodies were acid-dipped. 'The raw steel uni-body is called a body-in-white. Just before it goes into the primer tank they grab it off the assembly line. We got three and they were trucked to a chemical company in Long Beach, California, that would dip them in acid,' he explains. 'They pretty much knew how many seconds would take a thousandth off all the body surfaces. They did the work at about 10:00 p.m.--they would only do it at night because it would put a huge cloud of blackish gray smoke in the air. The whole body was put on a hook and submerged in the acid where it just sat and bubbled at stank. When they came out they were hosed down, sprayed with neutralizer, and shipped to Newtown Square. The process chemically removed--it was probably tens of thousandths--uniformly off of every steel surface. And of course it was lighter. The only problem was that on this occasion Mark convinced the guy to do it a little bit too long--and the roofs on all three cars were just a little bit different.' "

I chose to quote from Argetsinger's book because I believe it's the best printed record of the Donohue era at Penske Racing.

Amazing! and nobody has quoted THE UNFAIR ADVANTAGE. "Another thing was the vinyl top. We were constantly repainting our cars, and it cost about $400 just to paint the top alone. So we figured that a $50 vinyl roof ought to last the entire season. Well ... actually it wasn't just a cost consideration, because we had acid-dipped the top a little too heavily, and it was wrinkled enough so that it looked bad in paint. But it wasn't aluminum or chopped full of holes as some competitors claimed."

You're too hard on yourself, Jon. You've got jerks like me to do that! LOLBesides you should have at least taken yesterday as the last FULL day of vacation and not been getting into everything that's been posted while you were gone.

Isn't it amazing, the paranoia that existed between the teams at this time, that a vinyl roof should be so controversial. Donohue also ran wide flexible piping from his engine bay through the bodywork and doors which exited into the rear wheel wells to help extract heat from the engine bay. This also gained plenty of interest.

There was a lot of pressure to win if you were one of the factory-backed teams. That's where the paranoia and mistrust comes in. You don't want to have your opponent get any kind of advantage, real or perceived, because you could be out of a ride if your team ends up the loser.

As for wide flexible piping, I don't think I ever saw anything like that in use on the '69 Penske cars. I believe it was just holes lined up with one another between the doors and the quarters. If you've got a pic or two of any piping, I would love to see it.

I agree with there NOT being any piping, just the front to rear wheel well holes. As for the mistrust: THE UNFAIR ADVANAGE read is great; especially when Mark is talking about "The Red Light Kid", Chief Steward Dave Tallaksen.

You guys are right! I just went and checked, and as Jon has said, the Penske cars just had large holes that lined up through the bodywork, there was no piping involved. Apologies, it seems I was attempting to fabricate a new story!